As many as 64 people were killed and 143 wounded in a string of car bomb attacks in the Iraqi capital city alone, police said.

In the deadliest incident, at least 56 people were killed and 128 injured when two car bombs exploded near a funeral in Baghdad's Sadr City, police source said.

At least eight people were killed and 15 wounded when a car bomb went off in a popular market in Baghdad's Ur district, the source said.

Earlier Saturday, four suicide bombers wearing explosive belts blew themselves up at the entrance to the local headquarters of the Iraqi special police forces in Baiji, 200 km north of Baghdad, killing seven policemen, a local police source said.

No group immediately claimed responsibility for the attacks.

The blasts came a day after a bombing attack struck a Sunni mosque near the city of Samarra, 120 km north of Baghdad, killing at least 18 people while leaving 21 injured.

The UN Assistance Mission for Iraq said earlier this month that almost 5,000 civilians were killed and 12,000 injured in Iraq between January and August this year.